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STMicroelectronics ST779ACD-TR
- Part No.:
- ST779ACD-TR
- Manufacturer:
- STMicroelectronics
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
ST779ACD-TR.pdf
- Description:
- IC REG BOOST ADJ 300MA 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,276
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Product details
Overview
ST779ACD-TR from STMicroelectronics is an adjustable-output, synchronous step-up DC-DC converter optimized for low-voltage battery-powered systems. It delivers up to 300mA output current with 1V–6V input range, integrates a 1A NPN power switch and PNP synchronous rectifier, and features adjustable current limiting via ILIM pin for inductor optimization. Used in portable instrumentation requiring stable 2.7–6.5V regulated supply from single-cell alkaline or Li-ion sources.
For engineers reviewing the ST779ACD-TR datasheet, ST779ACD-TR pinout, ST779ACD-TR application, or ST779ACD-TR equivalent, key selection criteria include its shutdown-disconnect capability (20µA ISHDN), 1.23V feedback reference accuracy (±2%), adjustable current limit, efficiency at light load (82% @ 100mA), and SO-8 thermal resistance (160°C/W).
Technical Context
The ST779ACD-TR employs a fixed-frequency current-mode PWM controller with internal 1A NPN switch and complementary PNP synchronous rectifier. Its error amplifier compares the divided output voltage against a precise 1.23V reference, enabling output adjustment from 2.7V to 6.5V via external resistor divider on FB (Pin 8).
Shutdown mode fully disconnects the load by turning off both switch and rectifier, eliminating leakage paths. The ILIM pin allows peak inductor current programming from 1A down using a resistor to VIN, supporting cost-effective inductor selection without sacrificing short-circuit robustness.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 1V to 6V - guarantees startup under load from single-cell batteries (e.g., 1.2V NiMH, 1.5V alkaline, 2.7–4.2V Li-ion). |
| Output Voltage Range | 2.7V to 6.5V - set externally via FB pin; enables flexible rail generation without fixed-output variants. |
| Max Output Current | 300mA at VIN ≥ 2.4V - limited by package thermal dissipation (SO-8, Rthj-amb = 160°C/W) and internal 1A switch. |
| Feedback Reference | 1.23V ±2% - high-accuracy reference enables ±2.5% output regulation (e.g., 5.0V ±0.125V) with standard 1% resistors. |
| Supply Current (No Load) | 270µA - ultra-low quiescent current extends battery life in always-on sensor nodes and wearables. |
| Shutdown Current | 20µA - ensures near-zero battery drain during system sleep, critical for long-duration standby applications. |
| Switching Topology | Synchronous boost - eliminates external catch diode, improves efficiency by ~5–10% vs. asynchronous designs. |
Pinout & Package
ST779ACD-TR is housed in an SO-8 surface-mount package (5.0mm × 6.2mm, 1.27mm pitch), rated for 0°C to +85°C ambient operation with 160°C/W junction-to-ambient thermal resistance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - ILIM | Current limit programming input | Connects to VIN for 1A peak switch current; resistor to VIN sets lower limits-enables inductor derating and EMI control. |
| 2 - IN | Main power input | Accepts 1V–6V unregulated source; feeds internal switch and bias circuitry; requires local 22µF ceramic bypass. |
| 3 - AGND | Analog ground reference | Separate from PGND to isolate noise-sensitive feedback path; must be tied to PGND near device with low-inductance connection. |
| 4 - PGND | Power ground return | High-current return for switch and rectifier; requires direct solder to PCB ground plane to minimize voltage bounce and EMI. |
| 5 - LX | Switch node | Drives external inductor; carries pulsed 1A current; layout must minimize loop area to reduce radiated emissions. |
| 6 - OUT | Regulated output | Delivers up to 300mA; connects to 100µF output capacitor placed adjacent to pin to suppress ripple and transient response. |
| 7 - SHDN | Active-high shutdown control | Threshold at VIN/2 + 0.25V; asserts shutdown when pulled low, disconnecting load and reducing supply current to 20µA. |
| 8 - FB | Feedback input | Compares divided output against 1.23V reference; 50nA bias current allows use of high-value resistors (10kΩ–50kΩ) with minimal error. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated synchronous rectifier | Eliminates external Schottky diode, reduces conduction loss, and enables regulation even when VIN > VOUT. |
| Full load disconnection in shutdown | Both switch and rectifier turn off, breaking all current paths between IN and OUT-no parasitic discharge of backup capacitors. |
| Adjustable peak current limit | ILIM pin supports resistor-based scaling from 1A down, allowing optimized inductor selection for size, cost, and saturation margin. |
| Precision 1.23V feedback reference | ±2% tolerance over temperature enables tight output regulation without trimming; supports 1% resistor networks for ±2.5% total output error. |
| Low-noise layout support | Dedicated AGND/PGND pins and strict layout guidance (short traces, ground plane tie, capacitor placement) minimize switching noise coupling into analog circuits. |
Applications
| Portable Medical Sensors | Wireless Sensor Nodes |
|---|---|
|
Use Scenario: Single-cell coin-cell powered pulse oximeter with analog front-end and BLE radio. IC Role / Device Role / Timing Role: Step-up regulator generating stable 3.3V rail for ADC, op-amps, and RF transceiver from 1.8–3.0V battery. Use Value: 270µA no-load current and 20µA shutdown current extend battery life to >12 months in intermittent-sampling mode. |
Use Scenario: Battery-operated environmental monitor logging temperature/humidity and transmitting via sub-GHz ISM band. IC Role / Device Role / Timing Role: Adjustable 3.6V output supply for microcontroller and RF IC, dynamically scaled to match battery voltage decay. Use Value: Adjustable VOUT (2.7–6.5V) maintains optimal RF output power across full battery discharge curve without firmware intervention. |
| Handheld Test Equipment | Industrial Data Loggers |
|
Use Scenario: Pocket-sized multimeter with LCD backlight and precision analog measurement circuitry. IC Role / Device Role / Timing Role: Generates 5.0V rail for op-amp references and display driver from 1.5V alkaline cell. Use Value: Guaranteed 1V start-up and 82% efficiency at 100mA enable reliable operation even as battery voltage drops below 1.2V. |
Use Scenario: Ruggedized field logger using wide-temperature Li-SOCl₂ primary battery in remote monitoring installations. IC Role / Device Role / Timing Role: Provides regulated 3.3V supply for microcontroller, EEPROM, and isolated RS-485 transceiver. Use Value: SO-8 package with 160°C/W thermal resistance sustains 300mA output at +85°C ambient without derating-critical for sealed enclosures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar adjustable-output boost converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS61040DRBT | Higher 28V VIN max, but only 280mA IOUT; uses external MOSFETs; no integrated synchronous rectifier. | Lacks full load disconnect in shutdown (leakage path remains); less suitable for zero-drain standby. | Prefer when higher input voltage range is required and external FET layout is acceptable. |
| MAX17065ETA+ | Fixed 3.3V/5V outputs only; no adjustable FB pin; 400mA IOUT; integrated soft-start and OVP. | Cannot replace ST779ACD-TR where programmable output voltage is mandatory (e.g., adaptive rail scaling). | Choose when fixed output and enhanced protection features outweigh need for adjustability. |
Compared with TPS61040DRBT and MAX17065ETA+, the ST779ACD-TR uniquely combines adjustable output, true load isolation in shutdown, and ultra-low 20µA shutdown current-making it optimal for battery-constrained systems requiring flexible, low-leakage power conversion.
Availability
ST779ACD-TR is available at Aetrix Electronics and suitable for portable medical sensors, wireless sensor nodes, and handheld test equipment requiring stable component supply across extended product lifecycles.
Supply support for ST779ACD-TR includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, specializing in power management, microcontrollers, and analog ICs for industrial, automotive, and consumer markets.
The ST777/778/779 family was designed specifically for ultra-low-voltage, battery-powered portable electronics-emphasizing startup reliability, shutdown isolation, and minimal quiescent power consumption.
FAQ
What is the minimum input voltage required for the ST779ACD-TR to start regulation?
The ST779ACD-TR guarantees startup under load at 1V input (with ILOAD < 10mA). This is achieved through optimized internal biasing and low-threshold control circuitry, enabling operation from nearly depleted single-cell batteries. Startup behavior is verified across temperature (0°C to 85°C) and confirmed in the Absolute Maximum Ratings and Electrical Characteristics tables of the official datasheet.
Can the ST779ACD-TR be used with an output voltage below 2.7V?
No-the ST779ACD-TR's feedback comparator has a fixed 1.23V reference and minimum output specification of 2.7V. Attempting to set VOUT below this threshold results in loss of regulation due to insufficient headroom for the error amplifier and internal circuitry. The datasheet explicitly defines 2.7V as the lower bound of the adjustable output range.
How does the ILIM pin affect inductor selection?
The ILIM pin sets peak switch current: tying it directly to VIN configures 1A limit, while a resistor between ILIM and VIN scales it downward per Figure 16 in the datasheet. Lower peak current allows smaller, lower-cost inductors (e.g., 10µH instead of 22µH) with reduced saturation risk-but requires verification of ripple current and transient response under worst-case load steps.
Is AGND required to be connected to PGND, and if so, where?
Yes-AGND and PGND must be connected externally, but only at a single point located immediately adjacent to Pins 3 and 4 of the ST779ACD-TR. This star-ground connection prevents noise coupling from high-current PGND paths into the sensitive analog feedback circuitry referenced to AGND, as emphasized in the Layout Guidelines section of the datasheet.
ST779ACD-TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Function:
- Step-Up
- Output Configuration:
- Positive
- Topology:
- Boost
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 1V
- Voltage - Input (Max):
- 6V
- Voltage - Output (Min/Fixed):
- 2.7V
- Voltage - Output (Max):
- 6.5V
- Current - Output:
- 300mA (Switch)
- Frequency - Switching:
- -
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- 0°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
ST779ACD-TR FAQ
1.How can I place an order for ST779ACD-TR through Aetrix?
Please submit a Request for Quotation (RFQ) for ST779ACD-TR on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for ST779ACD-TR reliable?
The price and inventory of ST779ACD-TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ST779ACD-TR is usually 5 days.
3.What payment methods are accepted for ST779ACD-TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ST779ACD-TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ST779ACD-TR?
ST779ACD-TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ST779ACD-TR order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for ST779ACD-TR?
For technical support, including ST779ACD-TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ST779ACD-TR requirements.
6.How does Aetrix verify that ST779ACD-TR is sourced from the original manufacturer or authorized distributors?
All ST779ACD-TR products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that ST779ACD-TR meets industry standards.
7.What is the process for return or replacement of ST779ACD-TR?
All ST779ACD-TR units undergo pre-shipment inspection (PSI). If there is an issue with ST779ACD-TR, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The ST779ACD-TR part is unused and in its original packaging.
Return procedure for ST779ACD-TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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